Apparatus for forming dental crowns or the like



Oct. 27, 1936. C STAHL 2,058,838

APPARATUS FOR FORMING DENTAL GRWNS OR THE LIKE 7 Filed necfls less INVENTOR BY Carl @LACHZFBM ATTORN EYS Patented Oct. 27, 1936 UNITED STATES PATENT OFFICE APPARATUS FOR FORMING DENTAL CROWNS OR THE LIKE 6 Claims.

This invention relates to apparatus for forming dental crowns or the like.

One of the objects of this invention is to provide a method of forming dental crowns or the U like which is simple, practical and inexpensive in practice. Another object is to provide a method of the above character which may be practiced with a minimum amount of labor and with a great saving in time. Another object is to provide a method of the above character which may be practiced with simple and inexpensive tools. Another object is to provide a method of the above character whereby a dental crown of exact size and proportions may be easily produced. Another object is to provide a method by which a one-piece crown may be formed. Another object is to provide a method of the above character which will result in considerable savings in raw materials used. Another object of this invention is to provide apparatus for producing a dental crown or the like which will be practical and durable. Another object is to provide apparatus of the above character which may be easily manufactured in a minimum amount of time. Another object is to provide apparatus of the above character which will be light, small, easy to handle, and accurate in operation. Other objects will be in part obviousand in part pointed out hereinafter.

The invention accordingly consists in the features of construction, combinations of elements, arrangements of parts and in the several steps and relation and order of each of the same to one or more of the others, all as will be illustratively de scribed herein, and the scope of the application of which will be indicated in the following claims.

.In the accompanying drawing, in which is shown one of the various possible embodiments of my invention,

Figure l is a vertical sectional View of the cover of my apparatus;

Figure 2 is a top plan view of the container or mould forming a part of my apparatus;

Figure 3 is a perspective view of a tray or th like forming a part of my apparatus;

Figure 4 is a perspective view of the replica of a tooth as used in my apparatus and in the practice of my method;

Figure 5 is an exploded perspective view of the cover and container shown in Figures 1 and 2;

Figure 6 is a perspective View of the container andcover as held in the hand during the practice of mymethod;

Figure '7 is an exploded perspective view showing certain of the parts during one of the steps of my unique method;

Figure 8 is a vertical sectional view of my apparatus during one of the steps of my method, and

Figure 9 is a vertical sectional View of my apparatus during another step of my method.

Similar reference characters refer to similar parts throughout the several views of the drawing.

As conducive to a clearer understanding of certain features of this invention, it might here be pointed out that in the dental profession considerable difiiculty has been experienced in the formation of crowns or the like. Not only must these crowns be of exact size in order to provide a close fit over the teeth which they are to cover, but, also, they must be exact in shape in order to conform with the teeth with which they are to come into engagement. It is extremely difficult to form such a crown out of several individual pieces of metal, as, for example, gold, this operation being time consuming and costly. Thus a dentist who forms a crown in this fashion cannot accomplish it while the patient waits but must devote additional time to laboratory work. Also the tools required for such Work are numerous and complicated thus serving to increase the complexity of crown formation. One of the objects of this invention is to provide a method and apparatus for overcoming the above-mentioned difiiculties as well as many others.

Referring nowto Figure 2, there is shown a cup generally indicated at [0 and preferably formed from aluminum or some other metal having the characteristics thereof. The interior of cup 10 has four walls H, [2, l3 and I4 preferably tapering inwardly so that the bottom I5 is smaller in cross-section than the top thereof. Formed along the central portions of walls H and I3 are a pair of V-shaped projections I6 and I1 preferably running from the top of the cup to bottom I5. A recess l8 extends through wall 14 of the cup and the exterior of the cup is preferably enclosed by a covering l9 of vulcanite or the like. As best shown in Figures 1 and 5, I provide a cover generally indicated at 20 for cup I0 having a raised portion 2| formed on its under side. The sides of portion 2| are preferably tapered to conform in size and proportions with the interior of cup l0 and the top of opening H3. The sides 22 and 23 of cover 20, as best shown in Figure l, slope away from the raised central portion 24 thereof to form rests for a pair of fingers as will be described more fully hereinafter.

Thus central portion 24 of cover 20 extends in a direction substantially perpendicular to the axis of opening l8 when the top is in position on cup l0, it being understood that section 2la (Figure 5) of portion 21 fits within opening l8 so that the cover must be placed in this position on the cup. Heat resistant material 25 is disposed within cover 20 as best shown in Figure 1, portion 2i of the cover also preferably being formed from this material. A peg 26 is embedded in material 25 and extends downwardly from the bottom of portion 2 l.

Under certain circumstances I find it more desirable to employ a tray generally indicated at 21 (Figure 3). Tray 2'! is preferably formed from aluminium or the like and is provided with sloping sides to conform with the walls of cup ill. Thus the larger side of tray 2! is preferably the same dimension as portion 2| (Figure 5) so that the tray may be secured to portion 25 on cover 20 and inserted in cup iii as a part of the cover. Plastic material 28, as, for example, plaster of Paris, is disposed within tray 2? within which impressions of teeth generally indicated at 29 for which crowns or caps are to be made can be formed. Plastic material 28 may also hold replicas of portions of teeth according to the particular portion of my method being practiced. Tray 21 is also provided with a pair of grooves 30 and 3! to conform with projections I6 and H (Figure 2). Preferably plastic material 28 extends through tray 21 so that the tray may be secured to cover 26 by way of peg 26.

With the above-described apparatus I am able to practice my method in an efficient and practical manner. Thus I first produce an exact replica of the desired crown. If the crown is to cover the entire tooth, I prefer to employ a model 32 as shown in Figure 4. Model 32 is preferably the exact size and shape of the crown which I am to produce. I then take a strip 33 of tin foil or the like and wrap it about the side of model 32 from the top to the cusp portion 32d thereof, being sure that the strip 33 rests firmly against all portions of the model with which it is in engagement and is pressed down tightly against the border of the cusp portion of the tooth.

Having prepared the model, I secure it to cover 20 by way of peg 26 so that it assumes the position shown in Figure 5. Next cover 20 is clapped down upon the cup so that portion 2m extends along the top portion of opening l8. The cup and the cover are now grasped in the hand as shown in Figure 6. Thus the forefinger and middle finger of the hand preferably grasp the cover in engagement with sides 22 and 23 thereof while the thumb contacts the bottom of the cup so that opening I8 extends upwardly. In this position it is a very easy matter to pour molten metal into opening l8 which is the next step in my method. Preferably this metal has a low fusing point, an example of which is a metal known on the market as Melotte. After filling the interior of the cup, I continue to hold the apparatus in my hand while the metal cools into solid form which takes place in a very few moments. The vulcanite covering IQ of the cup and the heat resistant material 25 in the cover serve to prevent any excessive amount of heat transfer to the exterior of these parts and accordingly they may be held in the hand without any discomfort.

After the metal is cool, the cover is removed. leaving the model 32 in the metal and the solid piece of metal is also removed from the cup. This piece of metal has formed on its opposite sides a pair of grooves 34 and 35 (Figure 7) conforming with projections I 6 and I1 (Figure 2). Thus the piece of metal may be placed on its side or held in any convenient device and may be split in two by a chisel or the like forced into either of these grooves. Accordingly the solid piece of metal has now been split into two parts 35 and 32' and the model 32 has been removed therefrom.

The two parts 36 and 31 are now placed back in the cup l0 which forms a convenient holding device therefor. Thus together they form a die or the like having an impression 33 which is an exact replica of model 32. Next I take a cup 39 of gold or the like and of sufficient size to form the desired crown. I place in this cup a soft pliable material 40 which may be cotton and I have also found that shredded portions of a very soft wood are also suitable for this purpose. Above material 49 I prefer to place a layer M of sealing material, as, for example, guttapercha.

Cup 39 is now placed in impression 38 in the position shown in Figure 9 and. I take a peg 42 of suitable dimensions to engage layer 4| within the cup without damaging the sides thereof or the sides of the impression. By beating on peg (52 the pressure exerted on the material 40 forces the cup 39 to assume the exact shape and size of impression 38. The pieces of metal 36 and 31 are next removed from the cup and the crown is practically complete after the removal of layer 4| and material 40. Due to the fact that strip 33 (Figure l) was placed about model 32 at the start of my method, the cross-section of the completed crown is of sufficient size to slip over the tooth which it is to cap and still form an extremely firm and reliable fit therewith. The top of the crown may be cut and shaped to extend under the gum as desired, this being a simple operation after the complete formation of the crown all as described above.

Under certain circumstances it is more desirable to have a replica of the portion of the tooth to be covered in relief in metal, or, in other Words, the reverse of impression 38. This is often the case where a portion rather than the entirety of a tooth is to be covered or capped. To accomplish this, I form in any suitable manner the impression 29 in material 28 on tray 21. Tray 21 is then secured to cover 20, as described above, and the cover is placed on the top of the cup. The apparatus is then held, as described above, and after the metal has been poured through opening l8 into the cup and cooled the desired impression will appear on the top surface of the cool piece of metal. From this replica of the portion of the tooth to be covered, which is now formed in relief on the metal, I may make the desired cup by pressing a suitable piece of gold or the like down onto the metal so that it covers these portions and finally takes the exact shape thereof.

It is also easy to form an impression in a piece of metal of a portion of a tooth as distinguished from impression 38 which is of a complete tooth. Preferably this is accomplished by way of tray 21, a replica of the portion of the tooth being secured to or imbedded within material 28 and the tray placed in position as described above.

It will thus be seen that I have provided a thoroughly practical and efficient method and apparatus in which the several objects hereinabove referred to as well as many others are successfully accomplished.

As many possible embodiments may be made of the mechanical features of the above invention and as the art herein described might be varied in various parts, all without departing from the scope of the invention, it is to be understood that all matter hereinabove set forth or shown in the accompanying drawing is to be interpreted as illustrative and not in a limiting sense.

I claim:

1. In apparatus of the character described, in combination, a metallic receptacle, a heat. resistant covering disposed about said receptacle, said covering and the Wall of said receptacle having an aperture formed therein, a metallic lid for said receptacle, the interior of said lid being formed from heat resistant material, and a peg secured in said lid and extending therefrom, said peg adapted to hold the replica of a tooth suspended in said receptacle when said lid is in position.

2. In apparatus of the character described, in combination, a metallic receptacle, a heat resistant covering disposed about said receptacle, said covering and the wall of said receptacle having an aperture formed therein, a metallic lid for said receptacle, the interior of said lid being formed from heat resistant material, and a peg secured in said lid and extending therefrom, said peg adapted to hold the replica of a tooth suspended in said receptacle when said lid is in position, said lid having grooves on the top side thereof running substantially perpendicular to the axis of said aperture when said lidis in position.

3. In apparatus of the character described, in combination, a container having an aperture formed in one of its walls, a lid for said container, means for holding a replica of a tooth on said lid, and a frame-like piece capable of holding reproductions of teeth and being formed from heat resistant material, said holding means adapted to hold said frame on said lid within said container.

4. In apparatus of the character described, in combination, a container formed from metal suitable for moulding, said container having an aperture extending through one of its walls, a lid for said container, a portion of one side of said lid being in relief and substantially the shape of the interior of said container so as to fit therein, and means for fastening a model of a tooth to said lid, said lid having a raised portion running in a direction substantially perpendicular to the axis of said aperture so that the apparatus may be held with two fingers on the lid and the thumb on the bottom of said container with the aperture facing upwardly.

5. In apparatus of the character described, in combination, a container having an aperture formed in one of its walls, a lid for said container, means for holding a replica of a tooth on said lid, and a frame-like piece capable of holding reproductions of teeth, said holding means adapted to hold said frame on said lid within said container.

6. In apparatus of the character described, in combination, a metallic receptacle, a heat resistant covering disposed about said receptacle, said covering and. the wall of said receptacle having an aperture formed therein, two of the walls of said receptacle opposite each other having V-shaped projections formed thereon, a metallic lid for said receptacle, the interior of said lid being formed from heat resistant material, and a peg secured in said lid and extending therefrom said peg adapted to hold the replica of a tooth suspended in said receptacle when said lid is in position.

CARL STAHL. 

